1. Field of the Invention
The invention relates to an automatic valve, in particular a compressor valve or non-return valve, with a valve seat which includes passage channels for the controlled medium over which a shutter blade can be moved that comprises a lock element with concentric rings connected together by means of radial cross pieces and is guided by means of flexible guides, whose one end engages with the outer rim of the lock element and whose other end is fixed in position relative to the valve seat outside the lock element.
2. The Prior Art
Valves of this design are known and usually consist of a valve seat, a catcher which is arranged .at a distance from the valve seat, and moveable valve members which are arranged between the valve seat and the catcher, in particular a lock plate or shutter blade. In addition to valves with lock elements that slide along a guide surface, there exist valves with shutter blades which are guided without friction by means of flexible guides during their lifting motion. The flexible guides can be arranged either concentrically within the lock rings and engage internally at the lock element of the shutter blade or extend from the outer rim of the lock element. Their ends facing away from the lock element are fixed in position relative to the valve seat and the catcher; they can be clamped, e.g., between the valve seat and the catcher.
A valve guide of this kind is known from GB-PS 18 478 (1911). In this valve guide the lock element is a plate whose concentric rings are connected together by means of cross pieces which are offset in the circumferential direction. The plate is guided without friction by means of the flexible, outermost plate ring, which is bent up in the direction of the catcher and whose outer rim rests against the catcher. The width of this elastic guide ring is uneven. In the region of the cross pieces attached to the outermost plate ring, the guide ring is wider yet narrow at a distance thereof in order to increase its flexibility. Therefore, the plate can fracture in the region of the narrower ring sections and also in the region of the curvatures, having a relatively small radius, in the region of the cross pieces.
When the valve is open, the rings of the lock plate rest in a plane on the catcher, upon which they impinge relatively hard. The controlled medium, coming from the valve seat, impinges virtually vertically on the lock rings and is deflected twice at right angles before it leaves the passage slots of the catcher. The passage cross section of the valve depends on the size of the slots in the lock plate. On the whole, the result of the prevailing flow conditions is the formation of turbulence and back pressure phenomena which can cause, in addition to the limited passage cross section, a relatively high passage resistance for the medium flowing through the valve.
Another valve design is known from DE-A1-35 07 831 wherein the lock member consists of a spring tab. This springy tab controls the passage opening in the valve seat plate. Such valve tabs are formed by a steel spring leaf which extends usually over the entire surface of the valve seat plate. This design has no catcher and also no other end stop for the valve tab. When the valve, designed as a suction valve, is open, it projects freely into the cylindrical space. However, when the valve is open, the relatively wide sealing section also lies in the flow path of the controlled medium and thus causes back pressure, the formation of turbulence, and a two-fold deflection of the medium. Therefore, in this known valve the passage resistance is also relatively high. In addition, such valves which release only a small passage cross section for the controlled medium are suitable only for small and inexpensive compressors.
The invention is based on the problem of improving the known valves of the aforementioned design in a simple manner, so that the passage cross section for the controlled medium is enlarged and the flow conditions for the medium are improved, in order to decrease the passage resistance of the medium through the valve.